2010 21.5" vs 2009 24" for noise

[farmermac]

I have a 2009 24" which Apple rates at 21db for noise. The 2011 21.5" is rated at 18db. I don't know much about db ratings so this may be significant or not.

What bothers me most about the 24" is the fans. The computer is on 24/7 and the constant low level wooshing of the fans is noticeable. My MBP is much quieter in comparison.

So has anyone had a 24" and then switched to a 21.5" in a quiet environment?

Differences?

 

[SpeedFleX]

My Macbook 2008 13" is louder then my iMac 21,5", but the Harddrive can get pretty annoying on the iMac, this seem to have stopped ever since I told spotlight not to scan the boot camp partition